The slaughter in Pittsburgh was not "unimaginable." It was inevitable.

It was not inevitable just because anti-Semitic activity, including hate crimes in schools and bomb threats against Jewish institutions, has been soaring — up an unprecedented 57 percent last year, according to the Anti-Defamation League. That is the symptom. The cause is a climate in which the sentiments of white nationalists and other hate groups are no longer suppressed.

Hate groups feel emboldened to show their faces in public, as they did when they marched last year in Charlottesville, chanting: “Jews will not replace us.” That, too, had a deadly result. But the president of the United States insisted there had been moral equivalency between the neo-Nazis and those who had shown up to protest them: “There are two sides to a story. I thought what took place was a horrible moment for the country, but there are two sides to a story.”

In the Trump era, people who should be shunned are embraced, and made practically mainstream. Some who call themselves our political leaders even go out of their way to do it. This month, Rep. Steve King (R-Iowa) ventured into Canadian politics with an endorsement of Faith Goldy, a white-supremacist fringe candidate running for mayor of Toronto…